EDIT: V2 is out now, and it's a lot better! - LINK

After asking around on /r/360hacks it seems like nobody had done this or tried it before, at least from my research, so I decided to take a crack at it just for fun. Please read the info below for more details:

• This does not mimic the design or aesthetics of the original shell. The shape is fairly rudimentary, but maybe it can be more creatively detailed in the future if any talented folks want to remix this.

• This will probably only work with a trinity 360, possibly corona but unconfirmed (the trinity is the only model I own and it's what I referenced to design this. You are welcomed and encouraged to remix this design to accommodate other models and/or make improvements!)
  
   
• The XY dimensions of the shell are 229mm x 235mm x 64mm, its footprint just barely fits within the printable area of my Bambu Lab X1C. If you don't have an X1C/P1P/P1S/A1 (non-mini), then you will need to make sure your printer’s “printable area” can accommodate this.
  
   
• This design assumes you don't use or need the optical drive (mine is RGH3'd and everything I need is on the HDD). You will probably want to bridge these two pins together to make the system think the drive tray is closed, otherwise if the optical drive is not connected the system thinks the tray is stuck open.
  
   
• This design assumes you don't use or need the front USB ports. I only use OEM wireless controllers, the 3 ports on the back are enough for me, this results in the front face looking a lot cleaner, IMO it’s better than having a gaping rectangular hole on the front, especially since the front ports are so very recessed. Again, please feel free to remix this design to make changes if you want!
  
   
• You will need to ditch the plastic OEM fan shroud as it interferes with one of the top shell mounting poles. In my testing, I found the southbridge and NAND to receive sufficient cooling without it and found no thermal issues, cool air is being pulled into that area underneath the new HDD mount location from the vent holes on the left side of the shell, there is more ventilation than on the original OEM shell.
  
   
• The design of the shell results in the rear power input no longer being “keyed”, allowing you to potentially plug in the power input connector upside-down. DO NOT DO THIS. I used a label maker to make “FACE UP” and “FACE DOWN” labels to put on the top and bottom of the connector on the end of the power cable to serve as reminders when plugging it in.
  
   
• Dimension restrictions unfortunately resulted in eliminating the WiFi adapter. I only use ethernet anyway, but this is an important point to understand first before you decide to print this.
  
   
• You will need to do some soldering work for the external buttons, but it’s quick and simple. I found this image on some old forum where someone had figured out which points on the RF board could be soldered to for using external buttons. The larger hole on the front of the shell is for this 19mm momentary button which I am using for power, and the smaller hole is for this 12mm momentary button I am using for sync. You don't have to use these specific buttons, but if you use something different, you would need to modify the size of the holes to accommodate buttons of a different diameter.
  
   
• I ditched the original light diffuser ring that clips onto the RF board. Instead, I printed a 2-layer (0.4mm) tall, 40mm diameter cylinder in white PLA and tacked it in place to the inside of the top shell with a tiny bit of CA glue to act as a diffuser for the LED ring. In the 3mf file, this is included on the same plate as the HDD mount if you want to do the same.
  
   
• The new HDD mount replaces the original in order to relocate the HDD to a raised area where the optical drive used to be (you will need 4 screws to attach the 2.5” HDD/SSD to the mount). This is the only part that requires supports when printing.
  
   
• You will also need five M3 button-head screws (I used 16mm long) and five M3 heat-set threaded inserts. The inserts go into the ends of the "poles" that are attached to the top part of the shell (use a soldering iron to heat-press them into place). The screws are inserted from the underside of the "bed" of the shell and screw into these "poles" in order to attach the two shell halves together and sandwich the motherboard in place. Three of these screws & poles have the additional purpose of fixing the HDD mount in place. Don't tighten the screws too much or it will warp the bottom of the shell causing it to be lopsided and not sit flat. You will also probably want some adhesive rubber feet, or else the whole assembly will be resting on the 5 screw heads, which could scratch whatever surface it is sitting on.
  
   
• Optional: I also used these JST connectors to function as “inline disconnects” for the button wiring for if/when you need to disassemble the system in the future, but if your button wiring is long and flexible enough, it shouldn’t matter much. It’s up to you to decide if it’s worth it to do this part, it was just an idea I had.
  
   
• Yes, I did all this in TinkerCAD, and yes it was annoying. I haven’t invested the time to learn Fusion yet lol
  
   
• Why did I do this? I dunno. It doesn’t really “solve a problem”, I just wanted to get into designing and prototyping, and thought it would be fun to try making something that hadn’t been done before (at least to my knowledge, happy to be corrected on this if not). I suppose it would be useful to someone with a trinity console if their shell is in rough shape, and/or if they want to make it more compact and efficient.
  
   
• This is a “V1” design, intended to be a starting point that others more talented than me can remix to improve upon and come up with something more clever or creative in the future.

Feel free to ask any other questions you might have!